SASM and the Environment

The City of Mill Valley is privileged to have inherited a number of excellent online articles written by Mill Valley resident Alan Nayer. These articles give historical background and information about Mill Valley. We hope you enjoy these articles as you learn more about the amazing resources in and around our city. More articles can be found by visiting our Locations of Interest page

Gem Pond & SASM

Following are two related features. First, A Gem in Mill Valley is a story about a place in town not many people know about but is treasured by those who do. The second, SAZZEM, is a descriptive article about the City of Mill Valley department that plays a lead role in the first story.

A Gem in Mill Valley

The Accidental Pond

It is a rare story that contains both the words wildlife and sewage in it and does not end on a disheartening note. This, then, is a rare story, and its beginning can be traced to an accident that occurred in Mill Valley over twenty-four years ago.

The unlikely setting for the story is the Sewerage Agency of Southern Marin, or SASM, located near the Sycamore Avenue entrance to Bayfront Park in Mill Valley. The facility treats raw sewage from the surrounding area and pipes most of the treated water out to the Bay. In 1983, to handle the extra water that flows into the sewage system during winter storms, SASM built two dry ponds between its main building and the multi-use path in Bayfront Park. During periods of heavy rain SASM would store the excess wastewater in these ponds and after the rains ceased, draw the water back into the plant for treatment.

In December of 1984, a benign accident changed the face of the south dry pond. A leak developed that caused treated water to fill the pond to a level of one foot. It took a few months before the company that laid the pipes agreed that fixing the leak was their responsibility, and more time for them to actually perform the necessary repairs. During this period, waterfowl and shorebirds, beckoned by the fresh water and the quiet surroundings, began to visit the pond regularly. The immigration did not stop there though, for bird watchers and others finding a new, peaceful spot to commune with nature in the middle of civilization arrived soon thereafter. The birds brought on their feet and feathers and in their droppings seeds of cattails, sedges and other native California plants, some of which took root in this new, hospitable environment. A fresh water habitat, one of the few in Marin County, was born. Like any life form though, it was destined for many challenges in its future.

"Thoreau had his Walden Pond and I have the Mill Valley Sewerage Agency Pond"

David Coe, who was then Manager of SASM, candidly recalled his immediate reaction to this unexpected development. "I wanted to revert the pond to its dry state," he explained, "because I was concerned that it wouldn't be serving its original purpose of holding wastewater during periods of heavy rain," an undeniably important function for the welfare of the town and its residents. Coe said that two of his staff members convinced him to look into the possibility of maintaining both uses of the pond.

Coe approached the SASM Board, the group charged with overseeing the agency and consisting of one representative from each of the served districts. The Board had to consider this issue carefully. "Decisions regarding the pond are far from straightforward because it is not in SASM's charter to own, operate or maintain any public serving facilities." Nevertheless, the SASM Board thought "outside the box," and saw the benefits of keeping the south pond wet as long as its operational function was not disrupted. They hired an aquatic biologist as a consultant to determine the feasibility and impact of keeping the fresh water pond while maintaining its utilitarian purpose as an overflow basin.

Among the many people who regularly visited the pond from the 1980's onward was Ida Geary. Mrs. Geary, a long-tine resident of Mill Valley, taught classes on California native plants at San Francisco Community College, and was active in the Marin Audubon Society and the California Native Plant Society. In addition, she authored an environmental column, Naturally Speaking, for the Mill Valley Herald in the early 1990's. In some of her articles, she wrote about life at the pond, especially the discoveries of species not seen there before. Her fondness for the pond and its inhabitants was obvious. "Thoreau has his Walden Pond and I have the Mill Valley sewerage agency pond," she wrote in April 1991.

As the consultant was investigating the situation and preparing her report in 1985, Mrs. Geary and a handful of other nature enthusiasts who were anxious to maintain the pond's current state met informally from time to time with the SASM staff to keep abreast of the developments. The consultant's final report indicated that the pond was indeed hospitable to wildlife, and that periodic short periods of filling the pond with wastewater would not have a long-term impact on their environment. The fresh water pond, and its winged inhabitants, would stay.

Skateboarding and Bird Watching Don't Mix

Things went smoothly for the avian and human visitors to the pond until the summer of 1992, when public meetings at SASM were attended by Mill Valley parents and children desiring to cement over the north pond - the dry one - to use as a skateboard park. The people who frequented the adjacent south pond were concerned. While they saw the usefulness of a skateboard park for kids, they felt the noise and commotion it would generate would in effect end the fresh water habitat at the south pond. Birds, they argued, came not just because of the water but because of the safety they found there - the quiet place where they felt free to feed, play and bear and care for their young.

The people hoping to keep the north pond undeveloped formed the ad hoc group Friends of the Pond, and Mrs. Geary was asked to lead the campaign to fight for the status quo. She said though, "that I would work for it, not lead it." However, others who were there credit Mrs. Geary's organizing skills as the driving force behind the effort. Mrs. Geary made phone calls and sent out postcards notifying members when SASM public meetings would be held, and these meetings often overflowed with attendees from both sides of the issue. The Friends drew up a petition to keep the north pond as is, and fanned out all over town to collect signatures. "Our best idea I think was to visit the Bayfront Park dog run, because we were assured of lots of signatures from the pets' guardians, due to their affinity with the animals," said Mrs. Geary. Over 700 people eventually signed the petition.

The issue culminated in a heavily attended meeting at Mill Valley City Hall. Friends of the Pond brought several knowledgeable speakers to the meeting, including biologists from local universities and well-known Marin County naturalist Elizabeth Terwilliger, the namesake of WildCare, the Terwilliger Nature Education and Wildlife Rehabilitation Center in San Rafael. It turned out, however, that the debate did not have to come to a final vote based on just the pros and cons of the two parties' arguments. It was discovered that SASM could not get insurance coverage at the time for a city-hosted skateboard park, and the north basin remained an unpaved and quiet pond.

Of this issue Mrs. Geary, a long-time conservationist, related in an article in Mill Valley Magazine several years ago, "I found myself not facing bulldozers or lumber companies, but loving and earnest parents. As one parent said, the ducks are on the pond and the kids are on the street." Admitting that it could seem unfair to the children, she continued, "All I can say is that bird watching is just as legitimate a sport as skateboarding, as the enormous membership of the Audubon Society attests to." As a final suggestion, she offered, "I think that we can get together in Mill Valley and make a concerted effort to find a place in our town that would be suited for a skateboard facility, but would not deprive another group of their kind of recreation."

The Final(?) Challenge

Another person joins the story at this point. Sharon Salisbury is a long-time resident of Mill Valley who, in her own words, "just stumbled upon the pond one day in 1992." She became a regular visitor and then a staunch supporter of the refuge, joining in the unsuccessful campaign in mid-1994 to have a sign installed informing the public that it was a sensitive wildlife area. While working on a degree in wildlife management at College of Marin, she decided to choose the SASM pond as the topic of her assigned project paper in the ornithology class she was attending. "I was concerned about its future," she explained, "in addition to the compelling fact that California has only 4% of its original wetlands left."

While researching and writing the paper, she happened to meet Mrs. Geary at the pond one day in 1994. Although a frequent visitor to the pond, Salisbury had not been aware of the 1992 skateboard issue and its resolution in favor of keeping the fresh water pond until Mrs. Geary told her about it. Salisbury was, however, to play a pivotal role in the next challenge to the attempts to balance the wildlife habitat with the need for safe and thorough wastewater treatment.

Over the years, the native plants, particularly the cattails, multiplied and encroached upon the pond, hampering its function as a wastewater holding tank. In the mid-1990's, the SASM Board and staff decided it was time to revisit the issue of whether the pond could perform its intended use while doubling as a mini-wildlife preserve.

Friends of the Pond wanted their pond to remain in its current state, and once again mobilized in order to play a part in the decision-making process. Salisbury was key in organizing and publicizing this latest issue. She related some of her efforts for this cause: "I called Ida and enlisted her help. She and I made flyers and put them up around town. I called the Marin Independent Journal and asked them to send a reporter to write an article, which they did. I wrote a letter to the Herald and Pacific Sun announcing the November meeting of SASM and invited people to attend." She also asked some noted naturalists to the meeting, including her ornithology class instructor Joe Mueller, Bob Stewart from the Marin County Open Space District and Barbara Salzman from the Marin Audubon Society.

The meeting, according to Salisbury, was held on November 17, 1994, and attended by approximately 100 people. "I was astounded when I walked into the meeting to find the room filled to capacity and people flooding out into the hallway," she recalled. "I don't think the Board was quite prepared for such a turnout." Calm discussion was sometimes overshadowed by the passions of some of the people on both sides of the issue. "The debate became quite heated as there were a few Board Members who were still adamant about not turning the pond into a wildlife refuge and an audience that wouldn't take no for an answer," said Salisbury, adding, "One audience participant became quite abrasive," raising the room temperature further.

Born-Again Pond Lovers

The SASM Board and staff wanted more time to consider the issue and the comments presented, and the meeting was adjourned without a resolution. At the next meeting, in January 1995, the Board announced they would attempt to maintain the dual uses of the south pond. The Board proactively investigated the feasibility of instituting a formal management plan for the maintenance of the south pond, a plan that would ensure a good environment for the wildlife while not hampering the wastewater holding function of the pond. A consultant was hired to formulate the plan, and the finished product is still referenced today to maintain the pond.

Although Friends of the Pond and SASM had priorities that sometimes did not mesh, and non-avian feathers were ruffled at times, the relationship between them was generally not adversarial. Earlier in 1994, Salisbury had given copies of her completed ornithology class paper to the SASM Board members, but said, "I don't know if they read it." They apparently did. Her paper led to the creation of the management plan for the pond.

Today: Skateboarding, Signage, Ongoing Maintenance, and a Gem of a Pond

Some time after the skateboard park issue at the north pond ended, insurance industry rules for skateboarding liability coverage changed, and a temporary skateboard park was built near the former Mill Valley Recreation Center. This park had to be destroyed along with the Rec Center in 1998 to make room for the new Community Center. In December of 2001, the City of Mill Valley gave the go-ahead for a new skateboard park near Mill Valley Middle School. The Mill Valley Skate Park, located near Mill Valley Middle School, officially opened on June 7, 2003.

A kiosk with a sign describing the dual uses of the pond was unveiled in 1995. Additionally, although they were rejected when Salisbury requested them the prior year, three signs noting that the pond is a sensitive wildlife area were also installed at about the same time, around the perimeter of the pond. One of these signs has since been found damaged and has been removed.

The SASM Board, though now mostly made up of members who were not around during the previously described issues, still considers the double uses of the pond in their planning. In 2000, the Board decided it was imperative to increase the amount of wastewater that could be held in the south pond. However, instead of lowering the level of treated water, the Board prescribed the raising of the surrounding land, thereby increasing the holding volume of the south pond without any disruption to the wildlife's living quarters.

The introduction that Salisbury wrote in her class paper describes what she saw at the pond in the late winter and early spring of 1995, in an ostensibly non-emotional way that still leaves no doubt about her feelings for the birds she saw at the pond. "I was able to observe some wintering birds before they left for their northern breeding grounds, and was also able to watch breeding birds arrive and begin their courting ceremonies. Then there were the resident birds that I came to know and their different behaviors, in addition to cameo appearances by other birds who stopped by for a drink of water, or to rest." Last year was a special one for her and other birders. "A clapper rail was seen at the pond last year," she enthused. "This was quite an event as not only are they very endangered, this was apparently the first sighting of one using a fresh water pond rather than a salt water marsh." Salisbury nowadays visits the pond almost weekly.

Mrs. Geary said, "it is so ironic that now, instead of visiting pristine areas to view nature, we have to go to a sewerage pond," and one can't help but see the irony in the seemingly incongruous but welcome connection that exists in Mill Valley.
Many of the others who joined in the fight for the fresh water pond, and likely many people who discovered the 2-acre wildlife oasis more recently, definitely do visit the pond often, and have even bestowed a name on this little jewel on the grounds of a wastewater treatment plant. On the sign kiosk that SASM constructed near the pond, someone taped two sheets of paper containing a list of over 124 species of birds sighted at the pond. The heading on the list reads, "Gem Pond Bird List", and is dated "January, 2002." (The most recent list is dated February, 2007).


Most residents of a city or township tend to, even prefer to, ignore the usually government-run maintenance function that handles the processing of wastewater and raw sewage generated by the municipality. We decided to end this ignorance and jump, figuratively speaking, into Mill Valley's sewer system, following wastewater after it leaves the homes and businesses of Mill Valley and the surrounding area.

Built in 1979, the Sewerage Agency of Southern Marin, or SASM (pronounced “SAZZEM”), and its wastewater treatment facility are not situated in a deserted part of town, hidden away from Mill Valley residents. Those who frequent Mill Valley's Bayfront Park and multi-use path - bicyclists, skaters, bird watchers, strollers, soccer players, dogs and birds - probably know the SASM building at the Sycamore Avenue entrance to the park. In fact, those who arrive there by car might park within a few feet (and in winter, a few puddles) of its entrance. The treatment facility takes in all the wastewater produced not only in the City of Mill Valley, but also the neighboring unincorporated communities of Almonte, Alto, Homestead Valley, Strawberry, Tamalpais Valley and West Tiburon.

If you own a house in any of these areas, then, using a delicate example, wastewater from your kitchen sink goes down the drain and out through the plumbing probably located in your basement or under your land, to meet up with the municipally owned drainage pipes in the street. From there, often via a series of connections to other, larger pipes, all the wastewater winds up at SASM.

Here the wastewater undergoes physical, biological and chemical treatment until it is 95% rid of solid and organic waste and 100% free of pathogenic bacteria. The final leg of the effluent's journey is conveyed via six miles of pipeline straight to Elephant Rock at Point Tiburon, one of the southernmost points of Tiburon. At that point, a right turn in the pipe sends the water 900 feet out to Raccoon Strait, between Tiburon and Angel Island, where it is discharged into the San Francisco Bay.

A small percentage of the water, instead of traveling to the Bay, undergoes further treatment, called water reclamation, to make it suitable for human contact. This water is used to irrigate some of southern Marin's parks, including Hauke and Bayfront Parks in Mill Valley.

The solid and organic waste extracted from the wastewater is treated further, and most of it is transported to the Redwood Sanitary Landfill in Novato, to cover the garbage dumped there daily. During the summer, some of this waste is also transported to a landspreading site at Lakeville Highway and Highway 37 in Sonoma County.

The treated water is of course tested to ensure it meets all standards for dischargeable and irrigation water. Most verification is done with testing tools and chemicals, but Lab Analyst and Chemist Liz Falejczyk explained one of the final testing processes that uses neither. Each month, SASM adds twenty small fish to the treated water and the same number of similar fish to a control environment, to compare their survival rates. Falejczyk put it simply: "The test runs for 96 hours and the idea is to see how many fish die." We breathed easier when she noted, "These fish do very well in our effluent."

The preceding article about Gem Pond explained the need for the ponds dug near SASM. On a typical dry day, the treatment plant can expect a peak of about five million gallons of wastewater flowing into the facility from Mill Valley and southern Marin sanitary districts. The system currently has a capacity of 25 million gallons per day however on successive days of heavy rains as much as 30 million gallons can swamp SASM's facility. The ponds are used to temporarily hold excess sewage until the flow through the treatment plant ebbs, and SASM can safely draw back the water from the pond for treatment.

Many people believe that water flowing into municipal drains in our streets, such as rainwater or the water you use to wash your car or irrigate your garden, gets treated before returning to natural waterways, but this is not so. Liquid entering outdoor drains flows directly into Richardson Bay, a good reason to eliminate the use of pesticides and chemical fertilizers in your garden and refrain from washing your car in your driveway. (Commercial car washes by law must treat water used in the washing process before sending it on its way.)

Why then must SASM be prepared to handle extra wastewater during periods of heavy rain? Rainwater that does not flow into the street drains but instead follows its natural course underground is the culprit. The average age of Mill Valley's sewer pipes is 40 to 50 years, and the older pipes actually date back to the town's incorporation over a century ago. These aging pipes are breaking down, and many have leaks. Millions of gallons of rainwater per day that is soaked into the ground during storms seeps into the decaying pipes, joining the wastewater on its trip to SASM.

The capture and treatment of sewage is extremely important to a municipality, its residents and its wildlife, and it is a complex series of tasks. Knowing how the process works makes one appreciate the work of the many people behind the scenes who keep the system working, and the extra care we all must take to keep the environment safe.

Written by Alan Nayer. Text is © Alan Nayer.